Upper for a boot



FIG. 1 is a perspective view of a upper for a boot in accordance with my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof; and,

FIG. 6 is a top view thereof.

The broken lines shown in all of the figures form no part of the claimed design. 

CLAIM The ornamental design for a upper for a boot, as shown and described. 